You might want to check your state's curriculum standards. Generally in the US, 4th grade is state history...
California's standards did include the transcontinental railroad (along with Native Americans, the Spanish/Mexican Missions, the gold rush, then the transcon.
In Maryland their curriculum includes the B&O
Although not specifically in the curriculum, in southern Nevada we find 3rd grade teachers wanting to visit the our railroad museum because of its role in building Hoover Dam
Randy Hees
Director, Nevada State Railroad Museum, Boulder City, retired
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